Cartographie des zones inondées par imagerie spatiale radar, optique et modèles numériques de terrain : capacités et limites illustrées par des exemples en France (Aude 1999) et à l'étranger (Honduras 1998, Venezuela 1999 et Madagascar 2000)

Flood Mapping using spatial radar and optical imagery and digital elevation model : Limits and capacities.

¹ Géosciences Consultants, 157 rue des Blains 92220 Bagneux (France)
² Université Paris 7, laboratoire de Géographie Physique

Abstract

Spaceborne Synthetic Aperture Radar (SAR) images have opened new perspectives in the field of flood mapping and monitoring, specially with the reduction of the time between programmation and delivery of images to users. This reduction results mainly from the all weather and night & day acquisition capacity of radar satellites. ERS and RADARSAT satellites are the only operational sensors able to deliver commercially SAR images of any point of earth. ERS is favoured by a very high quality but a fixed incidence angle and a long return period. RADARSAT has a variable incidence sensor and very fast production flow capacity. These advantages are counterbalanced by specific difficulties due to image geometry and nature, making processing more difficult to automatize. Nevertheless, flood mapping with SAR get closer of users needs in crisis situation even if mapping of fast floods in areas with strong relief remains difficult.